1. Field of the Invention
The present invention relates to an airbag apparatus in which an inflatable airbag includes a check valve mechanism in order to prevent an internal pressure of a predetermined inflatable region from dropping.
2. Description of Related Art
It is known, as disclosed in JP 2010-143528 (paragraphs 0040-0057 and FIGS. 4-7), that an airbag of an airbag apparatus is internally provided with a check valve mechanism. The check valve mechanism is comprised of a closing wall that is located in a passage of an inflation gas and provided with a communication hole, and a valve panel that is formed of a flexible material and located in a periphery of the communication hole on a downstream side of the closing wall. With this configuration, when an inflation gas passes by, the valve panel is pushed by the inflation gas and separated from the periphery of the communication hole so as to allow the inflation gas to pass through the communication hole. Then if the inflation gas stops to pass through, an internal pressure of an inflated region of the airbag pushes the valve panel, such that the valve panel presses the communication hole and checks backflow of the inflation gas.
The above-described configuration makes the airbag compact in a folded-up configuration since the check valve mechanism is comprised of a flexible valve panel and the valve panel can be folded up together with the airbag.
However, in the conventional airbag apparatus described above, when a predetermined inflatable region of the airbag is to be inflated, an inflation gas going through the communication hole hits the periphery of the communication hole orthogonally. After passing through the communication hole, the gas further hits the valve panel directly. That is, the periphery of the communication hole and the valve panel form flow resistance and hinder quick inflation of the inflatable region.